Glassware, such as glass bottles, is typically made in a so-called individual section machine, which includes a plurality of identical sections that operate out of phase with each other to produce the glassware. Each section includes one or more blank or parison molds, in which gobs of molten glass are either pressed or blown to form blanks or parisons. Each parison is then removed from the blank mold and placed in a final-blow mold. A blowhead is lowered over the parison in the blow mold, and final-blow air is directed into the parison through the blowhead to form the parison against the internal surface of the final-blow mold. The blown articles of glassware are then removed from the molds.
Conventional blowheads include an air passage for feeding final-blow air from an inlet to the inside of the parison. One or more second passages branch from the first passage for feeding air around the outside surface of the preformed parison finish to cool the finish and support the finish against outward expansion during the blowing operation. Blowheads of this character have the drawback that the ratio of final-blow air to finish cooling air is determined by the ratio of the diameters of the air passages in the blowhead, as well as other fixed factors. Since the finish cooling air passages branch from the final-blow air passage within the blowhead, it is not possible to vary the ratio of the finish cooling air to the final blow air. It has therefore been proposed to provide a so-called dual-stage blowhead, also sometimes called an isolated finish blowhead, in which the finish cooling air passages are separate from the final-blow air passages and are provided with a separate inlet on the blowhead. The ratio of final-blow air to finish cooling air can be controlled and varied by feeding air at different flow rates and pressures to the final-blow and finish cooling inlets on the blowhead. It is a general object of the present invention to provide improvements in blowhead assemblies, preferably but not necessarily dual-stage blowhead assemblies, in which final-blow air is directed into the parison from directions that achieve improved results in the final blown product.
A blowhead assembly in accordance with a first aspect of the present invention, for receipt over a parison finish to blow the parison within a blow mold and simultaneously cool the parison finish, includes a blowhead body having a first chamber at one end for receipt over the finish of a parison in a blow mold, and at least one passage in the blowhead extending to the chamber from a first inlet for directing cooling air onto the external surface of a parison finish in the chamber. A second chamber in the blowhead body is spaced from the first chamber, and at least one second passage in the blowhead body extends to the second chamber from a second inlet for directing blow air into the second chamber. A first tube extends from the second chamber through the first chamber for receipt within a parison finish in the first chamber to feed blow air from the second chamber into the parison. A second tube extends from an exhaust passage in the blowhead body through the second chamber and through the first tube for receiving exhaust air from the parison. The second tube is coaxial with the first tube and extends beyond the free end of the first tube. The second tube has at least a free end that flares radially outwardly for deflecting blow air from the first tube radially outwardly within the parison.
A blowhead assembly in accordance with a second aspect of the present invention, for receipt over a parison finish in a glassware forming mold to blow the parison within the mold, includes a blowhead body having a passage for receiving blow air and a tube extending from the passage for receipt within the parison finish. The tube has open ends for directing blow air into the parison and radial passages for directing air against the internal surface of the parison finish. These radial passages preferably are disposed and angled to direct blow air against the finish where the finish abuts the opposing surface of the blowhead to help heal any plunger scar and prevent formation of a wire edge around the inside diameter of the finish mouth. This second aspect of the invention may be implemented in dual-stage blowheads in combination with the first aspect of the invention, or may be implemented in other types of blowheads.